Split resilient rings have been used for many years for restricting movement of one member relative another member most commonly when the one member is a cylindrical member such as a piston disposed within a bore of the other member.
In such case, either an annular outwardly facing groove is disposed in the outer surface of an inner cylindrical member or an inwardly facing annular groove is disposed on the inner surface of a bore surrounding the inner member and for the former of which the ring is contractively seated upon being released from a radially expanded state and for the latter of which the ring is expandingly seated upon being released from a radially contracted state.
Such split rings are commonly made by cutting a resilient material such as by stamping a suitable sheet metal and of which exemplary examples are disclosed in U.S. Pat. Nos. 2,382,947; 2,491,306; 2,509,081; 3,431,809; and 3,460,427 of which are incorporated herein by reference.
The split retaining ring in U.S. Pat. Nos. 2,382,947; 2,491,306 and 2,529,081 described above all have an opening or hole adjacent their free-ends on opposite sides of the split for receiving fingers of a manipulating tool therethrough for expanding and contracting the ring radially but which require that the fingers enter the openings from a side of the ring and be removed in the same manner. U.S. Pat. No. 3,460,427 discloses in FIGS. 1 and 3 a retaining ring having an elongate slot adjacent ends on opposite sides of the split that are respectively oriented at an acute angle relative the inner and outer peripheries of the ring for receiving fingers thereonto for either expanding or contracting the ring but which again must be inserted into and removed from the slot from a side of the ring.
FIG. 5 of U.S. Pat. No. 3,460,427 discloses the further practice of having openings that extend substantially transversely into each slot from the outer periphery of the ring which would only be accessible to the fingers in applications where the ring is to be seated in an annular groove surrounded by and in registration with an inner periphery of the ring.
The reverse is disclosed in U.S. Pat. No. 3,469,494 in which the retaining ring is provided with respective slots adjacent opposed ends in opposite sides of the split that respectively extend outwardly from the inner periphery in a direction angularly towards each other and thus can be utilized for engagement by fingers of a manipulating tool only for application where the ring is to be seated or is seated in a groove surrounded by the outer periphery of the ring in registration therewith.
Although the aforesaid patents collectively further disclose the practice of diminishing the thickness of the ring from a midpoint to each of the opposed ends to maintain circularity during expanding or contracting the ring as well as to offset the inner and outer peripheries so as to narrow the width of the midpoint and thereby reduce bending stress thereat during expanding or contracting the ring or vice versa to provide the broadest width at the midpoint between the opposite ends or provide a cross section whose thickness diminishes in a direction from the inner periphery to the outer periphery or vice versa or to provide the ring with a helical configuration such as a lock washer, none have disclosed or suggested providing slots respectively extending circumferentially into apertures through the ring from the opposed ends thereof facing towards each other across the split enabling fingers of a manipulating tool to be respectively moved circumferentially away from each other along the slots and enter the apertures for expanding or contracting the ring for use in either external or internal slots in registration therewith nor have they disclosed or suggested a tool by which to cut the ring to provide the profiled configuration herein described in connection therewith.